The present invention relates to power plants, and more particularly to a system for concentration of waste cooling tower blowdown in power plants.
Process discharges, particularly cooling tower blowdown, present difficult engineering, economic and environmental problems involving water treatment. Cooling tower blowdown or brine used in condensing steam to run a turbine in a power plant must be concentrated in some manner prior to final disposal. In the past, evaporation ponds have often been selected as a means to concentrate waste streams. However, wide swings in evaporation rates, high initial costs and environmental concerns have in recent years lead to a search for alternative technologies.
One alternative process for waste concentration involves vapor compression distillation. This process for concentrating cooling tower blowdown, however, initially requires high capital equipment costs, and since it utilizes electricity as the main energy source also results in high utility costs. Another alternative waste concentration process employs waste steam withdrawn from the main power plant condenser which is directed to an evaporator. Although equipment and utility costs for this latter process are less than that required for vapor compression distillation, these costs are still relatively high.